I think you should have a well comprehension of photography, framing and editing. "In The Blink Of An Eye" by Walter Murch will be a good start on the concept behind editing. I think editing is the key of storytelling. At the end is editing that will give the momentum and comprehension of your story. EDITING EDITING EDITING EDITING EDITING.
And when I say EDITING, is not about the F##@%$ computer software or any tools to actually edit. Is more about how to edit, how to make the audience experience your story, your picture.
As a director you MUST know how to do that, and sorry, most of it will happen in the editing room. You have to devote your self to the 3 amigos: WRITING, ACTING and EDITING. The rest is important, Lighting, props, makeup, costumes etc. But not as the 3 AMIGOS W. A. E. If you are not a writing director, at least, anderstand the mechanic of drama (not melodrama) in writing.
R.